* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 16px;
    line-height: 1.5;
    color: #f5f5f5;
    background-color: #262626;
}

.animation-container {
    position: relative;
    width: 100%;
    height: 200vh;
}

.animation-viewport {
    position: sticky;
    top: 0;
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

h1 {
    /* 三段渐变背景图 */
    background-image: linear-gradient(
        75deg,
        rgb(255, 255, 255) 0%,
        rgba(255, 255, 255, 1) 33.33%,
        transparent 66.67%,
        transparent 100%
    );
    /* 这里的 300% 100% 就是元素的三倍长 */
    background-size: 300% 100%;
    /* 初始阶段，以第三段透明背景作为元素的背景，隐藏文字不可见 */
    background-position-x: 100%;
    /* 文字形状裁剪背景图 */
    background-clip: text;
    -webkit-background-clip: text;
    color: transparent;
}
